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| United States Patent |
6,046,144
|
|
Karol
, et al.
|
April 4, 2000
|
Combination of phosphate based additives and sulfonate salts for
hydraulic fluids and lubricating compositions
Abstract
Disclosed are synergistic antioxidant compositions composed of (1) amine
salts of alkyl phosphates and (2) ethylenediamine, ammonium or metal salts
of alkylarylsulfonates.
The antioxidant compositions are useful for formulating zinc-free antiwear
hydraulic fluids and gear lubricating oils in conjunction with
thiophosphate type antiwear agents, corrosion and rust inhibitors.
| Inventors:
|
Karol; Thomas J. (Norwalk, CT);
Donnelly; Steven G. (New Fairfield, CT);
Stunkel; Brian W. (Stamford, CT)
|
| Assignee:
|
R.T. Vanderbilt Co., Inc. (Norwalk, CT)
|
| Appl. No.:
|
866963 |
| Filed:
|
June 2, 1997 |
| Current U.S. Class: |
508/279; 252/78.5; 508/408; 508/438 |
| Intern'l Class: |
C10M 141/10 |
| Field of Search: |
508/279,408,438
252/78.5
|
References Cited
U.S. Patent Documents
| 2578652 | Dec., 1951 | Cassaday | 260/461.
|
| 2763614 | Sep., 1956 | Cantrell et al. | 508/408.
|
| 2971912 | Feb., 1961 | Elliott et al. | 252/46.
|
| 3359203 | Dec., 1967 | O'Halloran | 252/46.
|
| 3658706 | Apr., 1972 | Meltsner | 252/49.
|
| 3791976 | Feb., 1974 | Messina | 252/75.
|
| 3843542 | Oct., 1974 | Adams | 252/75.
|
| 3876550 | Apr., 1975 | Holubec | 252/47.
|
| 3923669 | Dec., 1975 | Newingham et al. | 252/32.
|
| 3951829 | Apr., 1976 | Mullen et al. | 508/408.
|
| 4130494 | Dec., 1978 | Shaub | 252/32.
|
| 4225450 | Sep., 1980 | Rosenberger | 252/47.
|
| 4371447 | Feb., 1983 | Webb et al.
| |
| 4383931 | May., 1983 | Ryu et al. | 252/32.
|
| 4701273 | Oct., 1987 | Brady et al. | 252/32.
|
| 4791206 | Dec., 1988 | O'Neil et al. | 548/108.
|
| 4880551 | Nov., 1989 | Doe | 252/47.
|
| 5308521 | May., 1994 | Pavilon et al. | 252/49.
|
| 5362419 | Nov., 1994 | Zinke et al.
| |
| 5382374 | Jan., 1995 | Takemitsu et al. | 252/73.
|
| 5580482 | Dec., 1996 | Chasan et al. | 508/243.
|
| Foreign Patent Documents |
| 0821053 | Jan., 1998 | EP.
| |
| 1440129 | Oct., 1973 | GB.
| |
| 1518342 | May., 1975 | GB.
| |
Other References
English translation of claims of JPKokai No. 182,787/1990; Jul. 17, 1990.
|
Primary Examiner: Johnson; Jerry D.
Attorney, Agent or Firm: Baker Botts LLP
Claims
We claim:
1. A synergistic antioxidant composition for petroleum and mineral base
oils consisting of ( 1) amine salts of alkyl phosphate wherein the amine
is selected from ammonia, primary and secondary alkylamines or mixtures
thereof and (2) ammonium, ethylenediamine or metal salts of petroleum or
aromatic sulfonate wherein the metal is selected from alkali or alkaline
earth metals and the aromatic substituent is selected from alkylated
benzenes and alkylated naphthalenes having 1 to 4 alkyl groups of 8 to 20
carbons each, and wherein phosphate to sulfonate is present in the ratio
of about 14:1 to about 1:2.75.
2. A hydraulic oil composition comprising
(a) major amount of base oil;
(b) an oxidation inhibiting amount of a synergistic composition consisting
of (1) amine salts of alkyl phosphate wherein the amine is selected from
ammonia, primary and secondary alkylamines and (2) ethylenediamine,
ammonium or metal salts of petroleum or aromatic sulfonate wherein the
metal is selected from alkali or alkaline earth metals and the aromatic
substituent is selected from alkylated benzenes or alkylated naphthalenes
having 1 to 4 alkyl groups of 8 to 20 carbons each and wherein the ratio
of phosphate to sulfonate is about 14:1 to 1:2.75.
(c) a wear inhibiting amount of thiophosphate esters selected from the
group consisting of
(i) dialkyldithiophosphate succinates of the structural formula
##STR4##
wherein R and R.sup.1 are independently selected from alkyl groups having
3 to 8 carbon atoms,
(ii) dithiophosphoric acid esters of carboxylic acid of the formula
##STR5##
wherein R.sup.2 is alkyl having 3 to 8 carbon atoms and R.sup.3 is alkyl
having 2 to 8 carbon atoms, and
(iii) triphenylphosphorothionates of the formula
##STR6##
wherein n=1-2, m=2-3, R.sup.3 is alkyl having 1 to 20 carbon atoms,
R.sup.4 and R.sup.5 are hydrogen or alkyl groups;
(d) methylenebis(dialkyldithiocarbamate) wherein the alkyl group contains 4
to 8 carbon atoms;
(e) a metal deactivating amount of compositions selected from the group of
(i) triazole compounds selected from 1-(phenylaminomethyl) tolutriazole and
1-(phenylaminomethyl) benzotriazole wherein the phenyl group may have one
to three substituent groups selected from alkyl or arylalkyl groups and
mixtures thereof,
(ii) a composition consisting of benzotriazole and diphenylamine wherein
the diphenylamine is substituted by one to three alkyl or arylalkyl groups
or mixtures thereof and wherein the benzotriazole to diphenylamine is
present in the molar ratio of 1:1, and
(iii) a composition consisting of tolutriazole and diphenylamine wherein
the diphenylamine is substituted by one to three alkyl or arylalkyl groups
or mixtures thereof and wherein the tolutriazole to diphenylamine is
present in the molar ratio of 1:1; and
(f) a hindered phenolic antioxidant selected from the group consisting of
alkylated phenols having at least two alkyl substituents each having from
1 to 4 carbon atoms.
3. A composition according to claim 2 which further contains 0.02 to 1.0
percent of an organic acid selected from alkyl acid phosphate and
alkylarylsulfonic acid wherein the aryl group is benzene or naphthalene.
4. A composition according to claim 2 which contains corrosion inhibiting
amount of tolutriazole and 2-alkyl-1H-imidazole-1-ethanol.
5. A composition according to claim 2 wherein the total amount of additives
(a) to (f) are present in the amount of 1.0 to 5.0 percent.
6. Zinc-free antiwear hydraulic oil composition consisting of major amount
of base oil and minor amounts of functional additives
(a) 1,2-Dicarbobutoxyethyl 0,0-di-(2-ethylhexyl)phosphorodithioate;
(b) Methylenebis(dibutyldithiocarbamate);
(c) 1-(Di(4-octylphenyl)aminomethyl)tolutriazole;
(d) Butylated phenols;
(e) Calcium dialkylbenzenesulfonate;
(f) C.sub.12-14 -alkylamine isooctyl acid phosphate;
(g) a metal deactivating amount of compositions selected from the group of
(i) triazole compounds selected from 1-(phenylaminomethyl) tolutriazole and
1-(phenylaminomethyl) benzotriazole wherein the phenyl group may have one
to three substituent groups selected from alkyl or arylalkyl groups and
mixtures thereof,
(ii) a composition consisting of benzotriazole and diphenylamine wherein
the diphenylamine is substituted by one to three alkyl or arylalkyl groups
or mixtures thereof and wherein the benzotriazole to diphenylamine is
present in the molar ratio of 1:1, and
(iii) a composition consisting of tolutriazole and diphenylamine wherein
the diphenylamine is substituted by one to three alkyl or arylalkyl groups
or mixtures thereof and wherein the tolutriazole to diphenylamine is
present in the molar ratio of 1:1; and
(h) 2-Alkyl-1H-imidazole-1-ethanol.
7. Zinc-free antiwear hydraulic oil composition consisting of major amount
of base oil and minor amounts of functional additives
(a) 1,2-Dicarbobutoxyethyl 0,0-di-n-propylphosphorodithioate;
(b) Methylenebis (dibutyldithiocarbamate);
(c) 1-(Di(4-octylphenyl)aminomethyl)tolutriazole;
(d) Butylated phenols;
(e) Calcium dialkylbenzenesulfonate; and
(f) C.sub.12-14 -alkylamine isooctyl acid phosphate.
8. A composition according to claim 7 which contains optional corrosion
inhibitors selected from 2-alkyl-1H imidazole-1-ethanol wherein the alkyl
group contains 7-17 carbon atoms.
9. A gear lubricating oil composition comprising a major amount of
petroleum and mineral base oils of lubricating viscosity and 0.01 to 1.0
percent of a synergistic antioxidant composition consisting of (1) amine
salts of alkyl phosphate wherein the amine is selected from ammonia,
primary and secondary alkylamines or mixtures thereof and
(2) ammonium, ethylenediamine or metal salts of petroleum or aromatic
sulfonate wherein the metal is selected from alkali or alkaline earth
metals and the aromatic substituent is selected from alkylated benzenes
and alkylated naphthalenes having 1 to 4 alkyl groups of 8 to 20 carbons
each, and wherein phosphate to sulfonate is present in the ratio of about
14:1 to 1:2.75.
10. An antioxidant composition for base oils consisting of C.sub.12-14
-alkylamine isooctyl acid phosphate and calcium di-C.sub.10-18
-alkylbenzene sulfonate and wherein phosphate to sulfonate is present in
the ratio of about 14:1 to about 1:2.75.
11. A lubricating oil composition having improved filterability comprising
a major amount of base oil of lubricating viscosity and 0.01 to 1.0
percent of a synergistic antioxidant composition consisting of (1) amine
salts of alkyl phosphate wherein the amine is selected from ammonia,
primary and secondary alkylamines or mixtures thereof and
(2) ammonium, ethylenediamine or metal salts of petroleum or aromatic
sulfonate wherein the metal is selected from alkali or alkaline earth
metals and the aromatic substituent is selected from alkylated benzenes
and alkylated naphthalenes having 1 to 4 alkyl groups of 8 to 20 carbons
each, and wherein phosphate to sulfonate is present in the ratio of about
14:1 to 1:2.75, and containing organic acids selected from alkyl acid
phosphate and alkylarylsulfonic acid wherein the aryl group is benzene or
naphthalene.
Description
BACKGROUND OF THE INVENTION
The present invention concerns improved hydraulic fluids and lubricating
compositions. More particularly, there are provided novel combinations of
additives for imparting improved properties to hydraulic fluids and gear
lubricating compositions.
Hydraulic fluids are designed to transmit force and motion in a variety of
industrial machines. They are used in hydraulic systems where the fluid is
under pressure and in contact with moving parts. Often these moving parts
have fine tolerances, a variety of metallurgy and operate at high volume,
efficiency and pressure. Particularly desired characteristics of hydraulic
fluids are good resistance to oxidation, wear, rust and corrosion.
Deterioration of a hydraulic fluid caused by inadequate oxidation
inhibition will adversely affect the hydraulic oil and its ability to
transmit power efficiently and to lubricate the hydraulic system.
Filterability of a hydraulic oil can also be adversely affected if an oil
is contaminated with water. Poor filterability of a hydraulic oil in
contact with water will prevent the hydraulic system from transmitting
force to the hydraulic motors.
The hydraulic oil must also have the ability to separate from water.
Although small amounts of water can be tolerated, large amounts of water
can attribute to rust, oxidation, decreased ability to lubricate and
erratic pump action.
Because of the multifunctional nature of hydraulic oils, a commercially
acceptable hydraulic fluid composition must meet established industry
standards for all critical characteristics.
Particularly useful are antiwear hydraulic oils which possess wear
characteristics and many of the performance characteristics of lubricating
oils. In the past, antiwear hydraulic oils were formulated with zinc
compounds, such as dithiophosphates and the like.
In addition to zinc compounds, antiwear hydraulic oils contain a complement
of other additives necessary to prevent wear and deterioration of the
equipment while the oil transmits the required power and motion.
Lubricating compositions using zinc based antiwear additives contain other
functional additives necessary to perform the lubricating function for a
particular use. Thus, prior art teaches two different zinc based
compositions specifically designed either for application as hydraulic
fluids or for application as lubricants.
U.S. Pat. No. 4,383,931 teaches lubricating compositions containing the
combination of sulfurized oil and
methylenebis(dihydrocarbyldithiocarbamate) in conjunction with zinc
dihydrocarbyldithiophosphate.
U.S. Pat. No. 3,876,550 discloses similar multifunctional combinations
based on methylenebis(dihydrocarbyldithiocarbamate) in conjunction with a
rust inhibitor of the succinic acid type. U.S. Pat. No. 3,359,203 teaches
the use of adducts of dihydrocarbyldithiophosphoric acid and aliphatic
esters of maleic or fumaric acid in conjunction with phenol type
antioxidants.
U.S. Pat. No. 4,880,551 discloses a lubricating composition containing an
antioxidant synergist consisting of 1-[di(4-octylphenyl)aminomethyl]
tolutriazole, methylenebis(di-n-butyldithiocarbamate), and a phenolic
antioxidant
U.S. Pat. No. 4,130,494 teaches that the load carrying capacity of
synthetic lubricants is improved by adding a combination of organoamine
salt of phosphate ester and organosulfonic acid ammonium salt.
U.S. Pat. No. 4,225,450 discloses lubricants that are stabilized with
hydroxy-benzyl dithiocarbamates in conjunction with other lubricating
antioxidants such as aromatic amines, sterically hindered phenols, esters
of thiodipropionic acid, salts of dithiophosphoric acid, corrosion
inhibitors such as benzotriazole, organic amines, amine salts of
phosphoric acid partial esters, dinonylnaphthalenesulfonate salts and
others.
None of the above referenced lubricating compositions possess the hydraulic
function.
U.S. Pat. No. 3,658,706 discloses antioxidants for lubricating and
functional fluids consisting of phosphorothionates and
dihydrocarbylthioalkanoates.
Hydraulic oils contain metal corrosion inhibitors and rust inhibitors. U.S.
Pat. No. 2,971,912 discloses benzotriazole type metal corrosion
inhibitors. It is known to add sulfonate type rust inhibitors to zinc
containing hydraulic oils as disclosed in U.S. Pat. No. 3,843,542, U.S.
Pat. No. 3,923,669 and U.S. Pat. No. 3,791,976.
Environmental concerns linked to the toxicity of the heavy metal zinc has
rendered zinc containing hydraulic oils undesirable. Disadvantageously,
currently available antiwear hydraulic oils containing no or very low
amounts of zinc have limited commercial use. These so called ashless
antiwear hydraulic oils cannot satisfy all test standards; that is, they
do not possess the varied and balanced properties required of antiwear
hydraulic oils.
Surprisingly, it has been discovered that a synergistic combination of
certain phosphates and sulfonates together with other functional additives
impart to hydraulic oils the necessary balanced standard properties which
allow the oil to perform the desired hydraulic functions even in the
absence of zinc.
SUMMARY OF THE INVENTION
In accordance with the invention, there are provided synergistic
antioxidant compositions for base oils composed of (1) amine salts of
alkyl phosphates wherein the amine is selected from ammonia, primary and
secondary alkylamines and (2) ethylenediamine, ammonium or metal salts of
petroleum or aromatic sulfonate wherein the metal is selected from alkali
or alkaline earth metals and the aromatic substituent is selected from
alkylated benzenes and alkylated naphthalenes having 1 to 4 alkyl groups
of 8 to 20 carbons each and wherein the amount of phosphate to sulfonate
are present in critical ratios of about 14:1 to about 1:2.75.
An object of the invention is lubricating compositions comprising a major
amount of base oil and an oxidation inhibiting amount of the above defined
synergistic antioxidant composition.
Another object of the invention is hydraulic oil compositions comprising
(a) a major amount of base oil;
(b) an oxidation inhibiting amount of a synergistic antioxidant composition
consisting of (1) amine salts of alkyl phosphate wherein the amine is
selected from ammonia, primary and secondary alkylamines and (2)
ethylenediamine, ammonium or metal salts of petroleum or aromatic
sulfonate wherein the metal is selected from alkali or alkaline earth
metals and the aromatic substituent is selected from alkylated benzenes
and alkylated naphthalenes having 1 to 4 alkyl groups of 8 to 20 carbons
each and wherein the phosphate and sulfonate are present in critical
ratios;
(c) a wear inhibiting amount of thiophosphate esters selected from the
group consisting of
(i) dialkyldithiophosphate succinates of the structural formula
##STR1##
wherein R and R.sup.1 are independently selected from alkyl groups having
3 to 8 carbon atoms,
(ii) dithiophosphoric acid esters of carboxylic acid of the formula
##STR2##
wherein R.sup.2 is alkyl having 3 to 8 carbon atoms and R.sup.3 is alkyl
having 2 to 8 carbon atoms, and
(iii) triphenylphosphorothionates of the formula
##STR3##
wherein n=1-2, m=2-3, R.sup.3 is alkyl having 1 to 20 carbon atoms,
R.sup.4 and R.sup.5 are hydrogen or alkyl groups;
(d) methylenebis(dialkyldithiocarbamate) wherein the alkyl group contains 4
to 8 carbon atoms;
(e) a metal deactivating amount of compositions selected from the group of
(i) triazole compounds selected from 1-(phenylaminomethyl) tolutriazole and
1-(phenylaminomethyl) benzotriazole wherein the phenyl group may have one
to three substituent groups selected from alkyl or arylalkyl groups and
mixtures thereof,
(ii) a composition consisting of benzotriazole and diphenylamine wherein
the diphenylamine is substituted by one to three alkyl or arylalkyl groups
or mixtures thereof and wherein the benzotriazole to diphenylamine is
present in the molar ratio of 1:1, and
(iii) a composition consisting of tolutriazole and diphenylamine wherein
the diphenylamine is substituted by one to three alkyl or arylalkyl groups
or mixtures thereof and wherein the tolutriazole to diphenylamine is
present in the molar ratio of 1:1;
(f) a hindered phenolic antioxidant selected from the group consisting of
alkylated phenols having at least two alkyl substituents each having from
1 to 4 carbon atoms; and optionally
(g) alkyl acid phosphate, alkyl aryl sulfonic acid or mixtures thereof.
DETAILED DESCRIPTION OF THE INVENTION
The stabilized compositions of the invention are composed of known
commercially available ingredients which act synergistically as
antioxidants and together with other functional additives produce the
desired characteristics in antiwear hydraulic oils and gear lubricating
oils.
The synergistic amine salts of alkyl phosphates are prepared by known
methods, e.g. a method disclosed in U.S. Pat. No. 4,130,494. A suitable
mono-or diester of phosphoric acid or their mixtures is neutralized with
an amine. When mono-ester is used, two moles of the amine will be
required, while the diester will require one mole of the amine. In any
case, the amount of amine required can be controlled by monitoring the
neutral point of the reaction where the total acid number is essentially
equal to the total base number. Alternately, a neutralizing agent such as
ammonia or ethylenediamine can be added to the reaction.
The preferred phosphate esters are aliphatic esters, among others,
2-ethylhexyl, n-octyl, and hexyl mono-or diesters. The amines can be
selected from primary or secondary amines. Particularly preferred are
tert-alkyl amines having 10 to 24 carbon atoms. These amines are
commercially available as for example Primene.RTM. 81R manufactured by
Rohm and Haas Co.
The synergistic sulfonic acid salts are well known in the art and are
available commercially. Representative of the aromatic sulfonic acids that
can be used in preparing the synergists of the invention are alkylated
benzenesulfonic acids and alkylated naphthalenesulfonic acids having 1 to
4 alkyl groups of 8 to 20 carbons each. Particularly preferred are
naphthalenesulfonates substituted by alkyl groups having 9 to 18 carbons
each, as for example dinonylnaphthalenesulfonate.
The sulfonates are used in the form of neutralized salts of ammonia,
ethylenediamine, alkali metal or alkaline earth metals. Particularly
preferred are salts of basic calcium and basic lithium. The basic salts
are in the form of metal hydroxide molecule associated with the acid.
The synergistic composition acts as antioxidant and reduces the tendency of
the base oil to deteriorate and produce products of oxidation such as
sludge and deposits on metal parts. Thus, the ability of the oil to
lubricate and protect the integrity of the hydraulic system is not
compromised.
The synergistic antiwear composition is particularly compatible with
ashless antiwear agents of the dithiophosphate ester type. One class of
compounds are adducts of O,O-dialkyl-phosphorodithioates and esters of
maleic or fumaric acid. The compounds can be prepared by known methods as
described in U.S. Pat. No. 3,359,203, as for example O,O-di(2-ethylhexyl)
S-(1,2-dicarbobutoxyethyl) phosphorodithioate.
Another class of compounds useful to the invention are dithiophosphoric
acid esters of carboxylic acid esters. Preferred are alkyl esters having 2
to 8 carbon atoms, as for example
3-[[bis(1-methylethoxy)phosphinothioyl]thio] propionic acid ethyl ester. A
third class of ashless dithiophosphates of the invention are
triphenylphosphorothionates wherein the phenyl group may be substituted by
up to two alkyl groups. An example of this group, among others, is
triphenyl-phosphorothionate available commercially as IRGALUBE.RTM.TPPT
(manufactured by Ciba-Geigy).
Methylenebis(dialkyldithiocarbamate) compounds are commercially available.
For example, methylenebis(dibutyldithiocarbamate) is manufactured under
the trade name VANLUBE.RTM. 7723 by R. T. Vanderbilt Company, Inc.
The antioxidant and metal deactivating functions of the hydraulic oil are
further improved by the additives 1-[di(4-octylphenyl)aminomethyl]
tolutriazole and a hindered phenolic compound, both described in U.S. Pat.
No. 4,880,551.
The hindered phenols can be selected from 2,6-alkyl substituted phenols and
may carry up to four alkyl groups. Particularly preferred are
2,6-di-t-butylphenol, 2,6-di-t-butyl-4-sec-butylphenol,
2,6-di-t-butyl-4-methylphenol and butylated phenol mixtures.
Surprisingly, the filterability of the oil can be improved by adding to the
oil composition alkyl acid phosphate and aromatic sulfonic acid or
mixtures thereof. The alkyl acid phosphate may be di- and mono-alkyl acid
phosphate or mixtures thereof. The alkyl groups may be straight or
branched and contain 6 to 12 carbon atoms. The aromatic sulfonic acids can
be selected from alkylated arylsulfonic acids. Particularly preferred are
benzenesulfonic acids and naphthalenesulfonic acids substituted by 1 to 4
alkyl groups having 8 to 20 carbon atoms each.
The oil compositions may contain known corrosion inhibitors, rust
inhibitors and metal deactivators depending on the specific application
and equipment used. For example, corrosion inhibitors such as tolutriazole
and 2-alkyl-1H-imidazole-1-ethanol where the alkyl group contains 7-17
carbon atoms are suitable additives for hydraulic fluids.
The base oil of the hydraulic fluid can be selected from base oil stock of
petroleum oils and mineral oils. Premium mineral oils of high viscosity
are particularly suited for antiwear hydraulic fluids for use in most
hydraulic systems.
The base oil of gear lubricating oils can be base oil stock of mineral oil
or petroleum oil of lubricating viscosity as for example cycloparaffinic
and paraffinic stock oils. The lubricating oils can be also formulated
from synthetic bases as for example organic esters, polyglycols and olefin
oligomers. The lubricating oil compositions may contain viscosity index
improvers and dispersants.
The amount of the synergistic combination required to impart the
performance characteristics necessary to hydraulic oils may range from
about 0.01 to 5 percent of the weight of the total oil formulation. The
preferred range is about 0.05 to 0.20 percent based on the weight of the
total oil formulation. Although the individual components of the
synergistic combination are known in the art, the additives must, however,
be added in relatively high amounts. Surprisingly, it has been found that
by adding relatively low amounts of the synergistic combination satisfies
the industrial standards of antiwear hydraulic oils. This fact points
toward enhanced functional activity due to compatible interaction of the
synergistic combination with other components of the final hydraulic oil
formulation. Lubricating compositions may contain about 0.1 to 10 percent
of the synergistic composition depending on the intended use of the
lubricant.
The following examples are given for the purpose of further illustrating
the invention. All percentages and parts are based on weight unless
otherwise indicated.
EXAMPLE 1
Compositions of the invention were prepared by adding to the base oil
calcium di-C.sub.10-18 -alkylbenzenesulfonate and C.sub.12-14 -alklyl
primary amine isooctyl acid phosphate antioxidant synergists. A total of
0.15 percent of the synergistic composition was added by varying the
ratios of the sulfonate and phosphate synergists, as indicated in Table I.
Test sample 1 contained only the phosphate and sample 11 contained only
the sulfonate.
The primary amine used for neutralization of the phosphate was a commercial
product, Primene.RTM. 81-R manufactured by Rohm and Haas Co.
The base oil was Sunvis.RTM.21 manufactured by Sun Oil Co. In addition to
the synergistic antioxidants, the base oil contained 0.80 percent of a
mixture containing equal parts of methylenebis(dibutyldithiocarbamate),
1-(di(4-octylphenyl) aminomethyl)-tolutriazole, and commercial mixed
butylated phenols, Hitec.RTM. 4733 manufactured by Ethyl Corp. and
1,2-dicarbobutoxyethyl-0,0-di-n-propylphosphorodithioate.
The compositions were tested by the ASTM D2272 method. The test was
conducted with 50 gram samples at 150.degree. C. and initial oxygen
pressure of 620 kPa (90 psi). A "pass" oil has a high induction time. The
results were compiled in Table I.
Synergistic compositions of the invention, samples 3 through 9, show
improvement as compared to samples containing only one of the components
which failed the test. The optimum antioxidant function is shown in
samples 6, 7 and 8.
TABLE I
__________________________________________________________________________
Rotating Bomb Oxidation Test
Percent in Sample
Antioxidant Ingredient
1 2 3 4 5 6 7 8 9 10 11
__________________________________________________________________________
Calcium di-C.sub.10-18 -alkylbenzene-
-- 0.02
0.04
0.06
0.03
0.10
0.14
0.18
0.22
0.26
0.30
sulfonate (50% active)
C.sub.12-14 -amine isooctyl phosphate
0.30
0.28
0.26
0.24
0.22
0.20
0.16
0.12
0.08
0.04
--
(50% active)
Functional Properties
415
505
615
690
710
767
710
725
545
390
340
Average Induction Time, Min.
__________________________________________________________________________
EXAMPLE 2
Package compositions of additives for antiwear hydraulic oil were prepared
by blending the additives in the amounts given in Table II. The
compositions include the antioxidant synergists calcium di-C.sub.10-18
-alkylbenzenesulfonate and C.sub.12-14 -alkyl primary amine isooctyl acid
phosphate wherein the amine is a commercial product, Primene 81-R. About
one percent of the package compositions were added to the base oil, SUNVIS
21.
The compositions were subjected to the tests required for establishing the
standard specifications for industrially acceptable antiwear hydraulic
oil.
The oil compositions 14, 15 and 16 containing the synergistic antioxidant
composition contained other functional additives in critical amounts.
The oil compositions of the invention, samples 14 and 15, had balanced
properties that satisfied all of the varied requirements of antiwear
hydraulic oils.
The samples 12 and 13 containing only one of the antioxidants, did not pass
all the tests.
The results are compiled in Table II. The tests are described hereinbelow.
The Rotating Bomb Oxidation Test, ASTM D-2272 was performed as described in
Example 1.
The Four-Ball Wear Test was conducted according to the method described is
ASTM D4172. Four highly polished steel balls 12.7 mm in diameter were
placed in the tester and about 10 ml test sample was placed in the ball
pot, sufficient to cover the balls. The test was conducted at a rotation
speed of 1800 rpm under a load of 20 kg for 1 hour at 54.4.degree. C. The
scar diameter was measured to the nearest 0.01 mm.
Thermal stability was evaluated by a modified ASTM D2070 test for
determining the thermal stability of hydraulic oils. The test is known as
the Cincinnati Milacron method. Copper and steel rods in contact pith the
oil were evaluated for appearance and weight loss after 168 hours at
135.degree. C. Sludge was determined by filtering oil though No. 41
Whatman pad and 8 micron pad and weighing the residue. The total weight
was calculated by adding the weight of the filtrates to that of sludge
removed from copper rods. Viscosity change was determined by the ASTM
D-445 method and the neutralization number by the ASTM D-974 method. Test
samples 14 and 15 of the invention passed all of the above criteria as
given by the Cincinnati Milacron standard.
The Rust Inhibition Test was conducted by the ASTM D-665 method using the A
and B procedures. The test was conducted for 24 hours at 60.degree. C.
The ASTM D-943 oxidation test was conducted until test oil reached a total
acid number of 2 mg. KOH/g of oil at 95.degree. C.
The ASTM D-4310 sludge test was conducted for 1000 hours at 95.degree. C.
TABLE II
______________________________________
Antiwear Hydraulic Oil
Percent in Sample
Components 12 13 14 15
______________________________________
1,2-Dicarbobutoxyethyl 0,0-di-n-propyl-
0.2 0.2 0.2 --
phosphorodithioate
1,2-Dicarbobutoxyethyl 0,0-di(2-ethyl-
-- -- -- 0.2
hexyl)phosphorodithioate
Methylenebis(dibutyldithiocarbamate)
0.2 0.2 0.2 0.2
1-(Di(4-octylphenyl)amino-
0.2 0.2 0.2 0.2
methyl)tolutriazole (50%)
Butylated phenols (50%)
0.2 0.2 0.2 0.2
Calcium dialkylbenzenesulfonate (50%)
0.2 -- 0.1 0.1
Amine isooctyl acid phosphate
-- 0.2 0.1 0.1
Base oil 99.0 99.0 99.0 99.0
Functional Properties
4-Ball wear at 20 kg, scar diameter, mm
0.31 0.29 0.27
0.26
Thermal Stability Fail Fail Pass Pass
ASTM D-2272 Induction Time, minutes
662 338 730 600
ASTM D-665 Rust Test A/B
P/P P/P P/P P/P
ASTM D-943 Oxidation, hours
1700 4042 3210 2716
ASTM D-4310 Sludge, mg
200.2 8.6 16.8 20.8
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EXAMPLE 3
Gear oil compositions were prepared by adding the synergistic antioxidant
composition of the invention. The synergists were calcium di-C.sub.10-18
-alkylbenzenesulfonate and C.sub.12-14 -alkyl primary amine isooctyl acid
phosphate. The base oil was formulated with other functional additives
required to impart to the gear oil the required standard properties.
In addition, didodecylbenzene sulfonic acid and octyl acid phosphate were
added to improve the filterability of the gear oil composition. The base
oil used was NS oil manufactured by Shell Oil Company.
The test results are compiled in Table III.
The tests ASTM D 665B and the thermal stability test was conducted by the
methods described in Example 2.
Filterability of the samples was determined with apparatus consisting of
300 ml glass Millipore filter funnel with ground glass seal and stainless
steel membrane support to hold Millipore 1.2 micron pore size; 47 mm
filter diameter membrane. Test samples were prepared by mixing 300 ml test
sample with 0.35 g of distilled water. Filterability was determined by
measuring the time required to filter 300 ml test sample.
Hydraulic stability was determined by the ASTM D2619 method. A 75 g sample,
25 g water and copper test specimen were sealed in a pressure type bottle.
The bottle was rotated end for end for 48 hours in an oven at 93.degree.
C. The weight change of copper and the acidity of the water layer were
determined and compiled in Table III.
The Four Square Gear Oil Tester measures the wear protection
characteristics of a gear lubricating oil. The test gears are weighed and
secured on test shafts. The gear case is then charged with 1600 ml oil.
The test is run for 15 minutes at 1500 rpm at 90.degree. C.
The gear assembly is disassembled, weighed and reassembled for subsequent
testing. The test procedure is repeated through 12 load stages of testing
or until 10 mg of weight loss is recorded between two successive load
stages. A material passing through at least 10 stages affords good
antiwear properties for lubricating oils, as measured by this bench test.
The above embodiments have shown various aspects of the present invention.
Other variations will be evident to those skilled in the art. Such
modifications are intended to be within the scope of the invention as
defined by the appended claims.
TABLE III
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Hydraulic Oil Tests
Percent in Sample
Components 16 17
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1,2-Dicarbobutoxyethyl 0,0-di-n-propylphosphoro-
0.20 0.20
dithioate
Methylenebis(dibutyldithiocarbamate)
0.20 0.20
1-(Di(4-octylphenyl)aminomethyl)tolutriazole (50%)
0.20 0.20
Butylated phenols 0.20 0.20
Amine isooctyl acid phosphate
0.10 0.08
Calcium dialkylbenzenesulfonate (50%)
0.10 0.08
Didodecylbenzenesulfonic acid
-- 0.02
Isooctyl acid phosphate -- 0.02
Base oil 99.0 99.0
Functional Properties
Rust, ASTM D665B Pass Pass
Thermal Stability Pass --
Hydraulic Stability, ASTM D2619
Pass Pass
Cu weight loss, mg/cm.sup.2
0.01 0
Water/acid, mg KOH/g 1.0 2
Filterability Time for 300 ml, min.
Dry 6 6
Wet -- 23
Four Square Gear Oil Tester, Pass stage
10 11
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